Change speed mechanism



Sept. 17, 1935, P. F. MARTlNuzzl CHANGE SPEED MECHANISM Filed June l5,1933 5- Sheets-Sheet 1 Sept. 17, 1935, P. F, MARTINUZZI 2,014,905

CHANGE SPEED MECHANISM Filed June l5, 1953 5 Sheets-Sheet 2 Sept 17,1935. P. F. MARTINUZZI 2,014,905

CHANGE SPEED MECHANISM 105 in @Eenrum/Izzi E Patented Sept. 17, 1935 IUNITED STATES PATENT OFFICE CHANGE SPEED MECHANISM Application June 15,1933, Serial No. 675,965 In Great `Britain `Iune 20, 1932 3 Claims.

This invention comprises improvements in or relating to change, speedmechanisms. It is an object of the present invention to provide asimplified form of change speed gear box or boxes 5 of the type in whichthere are in effect two change speed mechanisms in series with oneanother.

The present invention comprises in a power transmission gear thecombination of a clutch, a speed change mechanism in series with theclutch and a second speed change mechanism of easy change type in serieswith and beyond the first from the clutch. The second speed changemechanism may be described as a relay gear which serves to double thenumber of speeds obl5 tainable from the first speed change mechanism.

It is a very important advantage of the arrangement described that thespeed change of the relay gear can be easily effected by an unskilledoperator and that by putting the relay gear into neutral the first speedchange mechanism becomes isolatable from both the load and the drivingforce, the one by the clutch and the other by the relay gear being inneutral, and thus speed changes of the first speed change mechanism are25 facilitated.

The term speed change mechanism of easy change type is used to indicatethe various types of mechanism in which variations of speed ratio aremore readily effected than when sliding gears 30 or dog clutches aloneare employed, as for example mechanisms in which the friction or likeclutches are used to engage the gears. One type of gear which answers tothis description is of the well-known epicyclic and band-brake type. A

35 type of easy change gear to which the invention easily lends itself,however, and the use of which forms a feature of the invention, is thatin which the gears are engaged by means of combined synchronizingfriction and positive dog clutches,

40 known as synchro-mesh gears. Such gears are described, for example inBritish Patent No. 342,824.

Preferably the first and second speed change mechanisms have theircontrols interlinked with 45 one another so that whenever the firstspeed change mechanism has a change of ratio brought into engagement thesecond mechanism must be in neutral. This arrangement does notnecessarily only apply in cases where a clutch is used 50 and thereforethe invention includes in a transmission gear the combination of twospeed change mechanisms in series with one another, whereof the onenearer to the source of power (or, Where a clutch is used, the onenearer to the clutch) is so controlled that engagement of a fresh speedin it can only be effected when the mechanism further fromy the engineor clutch is in the neutral position.

In one mechanical arrangement a single control lever is provided withoperative connections 5 to each' of the speed change mechanisms soarranged that movement of the control lever in one dimension bringsabout change of speed of one mechanism, while movement of the controllever in another dimension brings about change of 10 speed of the othermechanism, means preferably being provided whereby movement in thedimension to change the first mechanism (nearer to the source of poweror clutch) can be effected only when the speed change mechanism furtherfrom the source of power or clutch is in neutral.

When the change speed mechanisms are of the layshaft type it ispossible, and it constitutes a further feature of the present invention,so to arrange matters that one of the pairs of gears of the first speedchange mechanism also constitutes one of the pairs of gears of thesecond speed change mechanism. By this means the number of gears and theoverall length of the gear box is materially reduced without in any wayinterfering with the advantageous properties of the mechanism as awhole. In this construction it will be found that it is desirable thatthe pair of gears which serves as an element of both the speed changemechanisms should have a. ratio equal to or near to unity, in order thatthe various combinations of gears may give a suitably graded series ofratios.

The gear changing mechanism may be directly actuated by the controllever or the mechanism may be adapted to be actuated by fiuid pressure,for example compressed air or engine suction by means of a servocontrol, and the control may be preselective or automatic, ashereinafter described. '10

The accompanying drawings illustrate by way of example various possiblearrangements of gear box in accordance with the present invention.

In the drawings:

Figure 1 is a diagrammatic vertical section through one form of gearbox.

Figure 2 is a similar view of a second form. Figure 3 is a vertical andmore detailed section through a third form.

Figure 4 is a plan of the top of the gear box with the cover removed,certain of the parts being shown in section upon the line 4 4 of Figure3.

Figure 5 is a section upon the line 5-5 of 55 Figure 3 looking in thedirection of the arrows.

Figure 6 is a section upon the line 6--6 of Figure 3 looking in thedirection of the arrows.

Figure 7 is a detail indicating the arrangements for moving from forwardinto reverse gear and is taken upon the line of Figure 3, but drawn to alarger scale than that figure.

Figure 8 is a diagram of a servo-operated gear box.

Figure 9 is a diagram of the operating control lever of the mechanismillustrated in Figure 8. Referring to Figure 1, represents a casingwhich contains a first gear chamber I2 and a second gear chamber I3. Adriving shaft from the clutch I4 enters the first gear chamber at I5 andcarries a pinion I6 and dog teeth I1. An intermediate shaft I8journalled in a partition I8 between the gear chambers I2 and I3 islocated axially in line with the shaft I and journalled at in a bush inthe end of the shaft I5. The intermediate shaft carries a driven pinion2| having dog teeth 22 and it is splined at 23 to fit a sliding dogclutch member 24 having teeth to engage the dogs I1 and 22. Thus theintermediate shaft I8 may either be directly clutched to the shaft I5 oralternatively clutched to the pinion 2 I, which otherwise runs freelyupon it.

A layshaft 25 is journalled ln bearings below the shafts I5 and I8 andcarries fast upon it pinions 26, 21 which mesh respectively with thepinions I6 and 2|. The above described mechanism constitutes the firstspeed change mechanism of the gear and it will be seen that it is aspeed gear of the layshaft type giving either a direct drive when thedog clutch 24 is moved forwardly or an indirect drive at a lower speedwhen the dog clutch 24 is moved rearwardly.

The intermediate shaft I8 enters the second gear chamber I3 and carriesa pinion 28. It also houses the forward end 29 ofy a driven shaft 38 andthe driven shaft 30 carries at the back end of the box a pinion 3lmounted freely upon it. Between the pinions 28 and 3| there is a gearchange member 32 splined on the shaft 30 and carrying friction clutchfaces to engage alternatively with either the pinion 28 or the pinion3|. A second layshaft 232 lies below the shaft 30 and carries pinions33, 34 which mesh respectively with the pinions 28 and 3|. The slidingclutch member 32 is intended diagrammatically to illustrate an easychange clutch member of the synchro meshtype, that is t'o say of thetype which embodies synchronizing friction surfaces in combination withdog clutch members. The dog clutch members and the details, however, arenot illustrated herein inasmuch as they are well known in themselves andare described in the aforementioned British Patent Specification No.342,824.

It will be seen that the gears contained in the second gear chamber I3constitute a second twospeed mechanism of the layshaft type having aneasy change action and this second twospeed mechanism may be describedas a relay gear box, that is to say it serves to modify the effect ofthe speed changes brought about in the first gear box. Thus it doublesthe number of gears provided by the first gear box and it permits of aneasy change from the higher to the lower range of gears thus provided,whether the rst gear box be running on its higher gear or its lowergear. Moreover, if the relay gear is placed in neutral before the firstgear is shifted, even when no easy change" mechanism is provided in thefirst gear box the changing of gear in the first gear box is greatlyfacilitated because the gear is not only disconnectible from the driveby the clutch I4 but is also disconnected from the driven load by therelay gear being placed in neutral, and under these conditions a simple5 dog-change can be easily and noiselessly effected without great skillv It will be obvious that by interconnecting the controls of the twosliding change members 24 and 32 in a proper manner the described order10 of changing of the gears can be automatically ensured and a suitableconstruction for carrying this into effect in a practical way ishereinafter described in connection with the form of gear illustrated inFigures 3-7. 15

Figure 2 illustrates a modification of the gear shown in Figure 1 inwhich in effect the rear pair of gears 2|, 21 of the first gear box and.the front pair of gears 28, 33 of the second gear box are broughttogether as a single pair thus simplify- 20 ing the construction. l

In thisfgure a casing 48 is shown which is united to the casing aroundthe clutch 4I from which a driving shaft 42 enters the casing. Thedriving shaft 42 is splined and carries a gear 25 wheel 43 which slidesupon it and is provided with dog teeth 44. The driven shaft 45 in linewith the driving shaft 42 enters the casing 40 from the rear end and isjournalled at its forward end in the shaft 42. The driven shaft 45 30carries close to the end of the driving shaft 42 a pinion 46 having dogteeth 4`| which can be engaged with the dog teeth 44 on the pinion 43 ifthe latter is slid rearwardly into engagement therewith. The pinion 46also has C5 friction and dog teeth engagement with an easy change clutchmember 48 splined to the shaft 45. A second driven pinion 49 is mountedon the shaft 45 on the other side of the easy change clutch member 48.Below the shafts 42, 45 there 40 is a layshaft 50 having pinions 5I, 52solid with it for meshing respectively with the pinions 46, 49. Thisshaft also carries a pinion 53 which is slidable along the layshaft,meshes constantly with the pinion 43 and carries dog teeth 54 45 forengaging with corresponding dog teeth 55 on the shaft 50. It will beobserved that the pinions 43, 53 are of double helical form so that theytend to keep in engagement with one another during sliding movement andthatthe dog 50 teeth 54, 55 can be engaged by moving the pinionforwardly in the gear box while the dog teeth 44, 4`| between thepinions 43, 46 can be engaged by moving the sliding pinions rearwardlyin the gear box. 55 In this gear box the first speed is engaged bymoving the pinions 43, 53 forwardly to drive the layshaft 50 and thenengaging the easy change clutch member 48 with the pinion 49 so that thesmall pinion 52 drives the driven shaft 45 GO from the layshaft. Bymoving the easy change clutch member forwardly to engage the pinion 46the layshaft drives the driven shaft 45 at a. higher speed. Thisconstitutes second gear. Upon moving the easy change clutch member 48 toG5 neutral the sliding gear wheel 43 may readly be drawn backwards tocause the dogs 44, 41 to engage with one another and the pinion 46 isthen directly driven by the driving shaft 42. In this position if theeasy change clutch 48 70 is moved rearwardly the driven shaft 45 will beoperated through the gears 48, 5|, 52, 49, giving third speed, while onmoving the easy change clutch 48 forwardly to engage directly with thepinion 46 a direct drive from the shaft 42 to 75 the shaft 45 isinstituted giving top speed. By this means four speeds are obtained withonly three pa'rs of gear wheels and as in the case of {Figurel the easygear change is obtained on all four gears without the use of more thanone double easy change clutch member.

Figure 3 illustrates in somewhat greater detall a four speed changespeed gear on the same general lines as Figure 2 but differing in thatnone of the gears has any sliding movement. It is to be assumed that anengine and clutch are located (to the left of the figure) in the usualway and that the clutch drives a shaft 80 which is journalled by a ballbearing in the casing 6|. The shaft 60 is keyed to a pinion 62 and itcarries beyond the pinion dog teeth 63. In the end of the shaft isjournalled the front end 64 of a driven shaft 65.

Below the shafts 60, 65 and parallel theretd there extends stationaryspindle 66 on which is journalled a hollow layshaft 61 carrying a.freely rotatable pinion 68 which meshes with the pinion 62. The layshafthas keyed upon it a second pinion 69 carrying dog teeth 10 and thepinion 68 is provided with a hub 1| carrying splines 4 12 on whichslides a dog clutch member 13 which can be engaged when desired with thedog teeth 10 to lock the pinion 68 to the layshaft and the gear 69.

, The gear 69 meshes constantly with a pinion 14 mounted on the drivenshaft 65 with an interposed needle-roller bearing 15. The pinion 14carries splines 16 on which slldes a dog clutch member 11 for engagementwhen desired with the dog teeth 63 on the end of the driving shaft 60.'I'he dog clutch members 13, 11 are engaged respectively with forks 18,19 on a sliding rod 80 so that they are operated together and the clutch11 is engaged to lock the pinion 14 to the driving shaft 60 only whenthe clutch 13 is free and vice versa. This arrangement of pinionsconstitutes the rst speed change mechanism of the gear giving either adirect drive or a low speed drive to the driven pinion 14. Also mountedto rotate freely on the driven shaft 65 is a pinion 8| which is inconstant mesh with a pinion 82 cut in the end of the layshaft 61. Thepinions 14, 8| carry friction clutch surfaces 83, 84 and dog teeth85, 86for engagement with an easy change gear member 81 splined on the shaft65 and located between the two pinions. This mechanism constitutes thesecond speed change mechanism of the gear and permits the drive to betaken.\from the pinion 14 either through the layshaft d the gears 82, 8|vor directly from the pinion 4 through the clutch member 81 to thedriven shaft. The easy change clutch member 81 carries an operatingcollar 88 which is engaged by a fork 89 on a longitudinally movableshift rod 90 which is parallel with the previously described rod 80 buton the opposite side of the gear box as clearly seen in Figure 4. v Inthe gear now being described the reverse drive is provided for bycutting a reverse drive pinion 9| on the layshaft 61 and mounting aco-operating reverse pinion 92 on the driven shaft 65. As best seen inFigure 6 a sliding pinion 93 on a reverse layshaft 94 serves to connectthe pinions 9| and 92 when reverse gear is to be operated. The reversepinion 93 is controlled by a fork 95 carried on a hub 98 which slides ona rod 91 spanning the cover portion 98 of the gear box at a slightlyhigher level than the shift rods 80, 90.

The changing of the gears is effected by means of a gear lever |00mounted in a universal joint I 0| at the top of an upward tubularextension of the gear box cover 98. Control of the gears is so effectedthat they can only be moved in the order hereinbefore described, that isto say, the

easy change clutch member 81 must be in neutral whenever the dogclutches 13, 11 are moved. To this end it is arranged that the shift rod80 of the dog clutches 13, 1'L`is moved by transverse movements of thegear level00, while the shift rod 90 of the easy change gear lever ismoved by fore-and-aft movements of the gear lever |00. The bottom end ofthe gear lever |00 lies in a. fork .|02 (Figures 4 and 6) in one arm ofa bell crank lever |03. The other arm of the bell crank lever works in afork` |04 carried in the rod 80. Thus transverse movements of th'e gearlever operate the dogs 13, 11 to effect speed change in the first speedchange mechanism of the gear.

A pin 200 slidable in a supporting sleeve 20| has rounded ends one ofwhich is adapted to register with a groove 202 in rod 90 and the otherof which is adapted to register with either of the grooves 203, 204 inrod 80. As above de? scribed, transverse movements of lever |00 eifect amovement, one way or the other, of rod 80 to operate dogs 13 or 11.Movement of rod 80 brings groove 203 or 204 into regis/ ter with pin 200and this can slide into the groove when rod 90 is subsequently moved bylongitudinal movements of the lever |00 to engage thev clutch member 81.Once the lower end of pin 200 is moved out of the groove 202 the vrod 80is locked; in other words the arrangement constitutes a stop means suchthat unless the clutch member 81 is in neutral, with groove 202'registering with pin 200, the rod 80, and consequently the dogs 13 and11 cannot be moved.`

The sliding rod 90 which controls the easy change clutch member 81carries an upstanding arm |05 having a fork |06 at its upper end whichengages a boss |01 on the gear lever |00. By this means fore-and-aftmovements of the gear lever move the easy change clutch 81 and owing tothe use of the fork |06 the transverse movements for operating the `rstspeed change mechanism are not interfered with. A gate |08 is providednear the bottom of the upward extension of the cover 98, which gate isbest seen in Figures 5 and '1, the gear lever |00 being indicated insection at the mid-point of its movement. It will be seen that thetransverse movementto change the rst speed change mechanism can' only beeffected when the gear lever has been brought to its mid position in aforeand-aft direction in which' position the easy change clutch 81 is inneutral.

Thus the gate provides an additional guide to ensure that the easychange clutch is in neutral when the first clutch is operated: in otherwords it constitutes a further stop means to pre;j vent actuation of thecontrol lever |00 to operate clutches 13 and 11 unless and until clutch81 is in neutral. On this gate the gear positions are numbered 2, 3, 4,representing the rst, second, third and top gear positions of the leverrespectively and it will be seen that not only is the gear caused tofunction in the desired manner but that these positions correspond tothe normal positions of the gear control lever for a four speed gearbox, bearing in mind that the gate is located below the universal joint|0| and that the positions of the control knob of the gear lever |00 aretherefore reversed and inverted compared with the positions shown in thegate.

If the gears are cut with helical teeth in order to ensure silentrunning care should be taken in cutting the teeth on the pinions 69 and14 to see that the direction of the spiral is such that,

' tion of the figure, since the pinion 14 is a driving pinion only whenit is locked directly to the driving shaft 60 by the dog clutch 11, theeffect of kdesigning the helical teeth as described is to cause the endthrust to be taken against the end of the driven shaft when the\pinion14 is driving and under these conditions there is no relative movementof rotation between the pinion and the driving shaft when the thrust istaken, on the other hand thrust is taken against a collar |65 on thedrivenA shaft when the pinion 14 is beim driven. Under this lattercondition the pinion 14 is locked by the clutch member 81 to the drivenshaft and thus again there is no relative movement of rotation at theplace where the thrust is taken. Expensive thrust bearings are thusavoided.

A reverse notch ||0 is provided in the gate which is peculiarly shapedand located so that when the reverse gear is engaged the direct gearsare left in neutral. This action can best be seen by reference to Figure7, taken in conjunction with Figure 4. It will be observed that whenfirst the gear lever is moving from the neutral position towards theentry into the'reverse slot, the gear lever shifts the bell crank lever|03 and the sliding rod to engage the dog clutch 13 with the layshaft61. It then moves forwardly a little towards the No. 1 position of thegate and thereby becomes disengaged from the fork |02 of the bell cranklever |03. This permits the gear lever to move further over and enterthe reverse slot ||0 of the gate, leaving the layshaft 61 in gear.During this time, and bearing in mind that the boss |01 of the gearlever lies nearer to its centre of motion than does the fork |02 belowit, the boss |01 will remain in the fork |06. Consequently the rod isshifted a little to the right. as viewed in the figure, but not enoughto carry its central notch out of the range of the centering ball(Figure 4). As the gear lever moves diagonally along the entering partof the reverse notch ||0 it slides diagonally out of the rear side ofthe fork |06 which is shorter than the front side thereof and bevelledas shown at 2 (Figure 7). The lateral movement of the gear leveraccompanying this motion engages the lower end of it in the notch |96 inthe hub 96 of the reverse fork 95 and the final longitudinal movementslides the gear' 93 into place.

On reversing the movement to get back into neutral, but for the factthat, as already mentioned, one side of the fork |06 is longer than theother, there would be some chance that the boss |01 would not get backinto the fork |06. Owing, however, to the fact that as shown at |3 oneside of the fork is prolonged, it lies in the path of the returning boss|01, meets it face to face and then as the gear lever moves diagonallyout of the reverse slot the fork |06 is moved rearwardly with it andfull re-engagement with the Referring to Figures 8 and 9, |20 represents10 the crank-case of an engine to which is bolted a, clutch chamber |2|,a casing |22 containing a first speed change mechanism and a secondcasing |23 containing a second speed change mechanism, the first andsecond speed change mechanism being supposed to be constructed in anyrof the ways hereinbefore described. A clutch operating lever |24 isprovided and a. link |25 connects the same to a valve |26 in a suctionor fluid pressure pipe |21 so that the pipe is opened 20 only when theclutch is disengaged.

Two double acting servo motors are provided one for operating one gearchange and the other for operating the other. The front servo motor hascylinders Z8, |29 for operating the first speed 25 change mechanism andthe second motor has cylinders |30, |3| for operating the second speedchange mechanism. The cylinders are opposed and single acting andcontain pistons which are linked together so that the two pistons in thecylinders |28, |29 operate a speed change arm |32 for the firstmechanism while the pistons in' the cylinders |30, |3| operate a speedchange `arm |33 for the second mechanism.

A control valve |34 is provided which contains two piston valves |35,|36 and the piston valves |35, |36 are linked to the respective servomotor` mechanisms by floating levers |31, |38 connected` at one endrespectively to the arms |33, |32 and at the other end to the valves 35,|36. To the 40 It will be seen that the link |39 is directly con- 4nected to the lower end of the gear lever |4| (which is pivoteduniversally at its centre |42), while the link |40 is connected to thegear lever through a bell crank lever |43 having a longitudinal slot |44so that the link 40 is operated by transverse movements of the gearlever.

The suction or pressure pipe |21 has` a branch |50 which enters thevalve casing |34 and is controlled by an interlock portion of the valve|36r which governs the flow through an interlock port |5| to themotor-controlling chamber |52 of the valve |35. Fluid pressure orsuction can be connected, by the valve |35, when it moves either to theleft or to the right with either the cylinder |30 or with the cylinder|3|, the atmosphere being at the same time put into communication withthe other cylinder.

A second branch |53 of the pipe |21 is connected through an interlockpassage |54 by the valve |35 with the chamber |55 of the valve |36 whichsimilarly controls the two cylinders |28, |29 of the first gear.

It will be seen that assuming the gear lever |4| is in the neutralposition-shown in Figure 9 of the drawings, movement to the right orleft will shift the link |40 so that the floating lever |38 is movedeither to the right or left as viewed in Figure 8. This will open one orother of the cylinders |28, |29 to the interlock passage |54.

No change in the gear is thereby effected, how- 75 eve1', because theiiud flow is cut off firstly by the cylindrical portion |56 of the valve|35 and secondly by the plug valve |26. Movement of the gear lever in afore-andaft direction will now operate the link |39 and shift the valve|35 either to the left or the right in Figure 8. This sets servo motorcylinders |30 or |3| as the case may be for action and opens theinterlock passage |54 leading to the control chamber |55 of the firstgear change mechanism. The Y.gear is thus preselected and as soon as theclutch pedal |24 is depressed fluid iiows through the passage |53, theinterlock passage |54 and the chamber |55 to the appropriate cylinder|28 or |29 and the first speed change mechanism is operated, the secondspeed mechanism meanwhile remaining at neutral because the interlockpassage has been closed by the movement of the valve |36. As soon as thevalve |36 has been restored to its initial position by the operation ofthe servo motor |28, |29, which means that the first speed changemechanism has been engaged, the passage through the branch |50 andinterlock pas-` sage |5| is opened and the second servo motor now movesto engage the second speed change mechanism, which it will beremembered, is of easy change type. Upon the clutch pedal being releasedthe drive is taken up. To move into the next higher gear the gear lever|4| is merely moved to the other end of the longitudinal control slot inthe gate |60 and when next the clutch pedal is depressed the servo motor30, |3| will move the easy change gear over into the other position, theport which connects the passages |50, |5| being already open for thispurpose since the gear lever has not moved the link |38 in thisoperation and the valve |36 remains in the position in which it issho'wn in Figure 8.

To change from a gear in one of the longitudinal slots ofthe gate |60 toa gear in the other of the longitudinal slots the gear lever |4| ismerely moved across to the appropriate notch in the diagonally remotecorner from the last gear and this moves both the valve |35 and thevalve 36. The movement of both these valves is equal to double thatwhich occurs in moving from the neutral position shown in Figure 9 toany one of the corners of the gate and this is, therefore= sufficient tobring one of the grooves |51 or |58 of the valve |36 opposite the branch|50 and to bring one of the cylindrical portions |59, |49 of the valve|35 opposite the port |53. The rst effect will therefore be, seeing thatthe branch |50 is open to cause the servo motor |30, |3| to move intothe neutral position. This will cause it to open the interlock passage|54 and the servo motor |28, 29 will likewise move into the neutralposition. In so doing it will close the branch |50 leading to the servomotor |30, |3| and prevent the latter from moving further until theservo motor |28, |29 has moved into the other gear in which position itagain opens the transverse passage |5| and the servo motor |30, |3|finally moves into the new gear.

It will be understood that the details of the lap and lead of the valves|35, |36 in relation to the ports shown need to be properly proportionedto ensure operation in the manner described and that owing to the smallscale of the parts the proper proportions are not accurately indicatedin the figure.

If it is desired to use a preselector lever mounted, say, upon thesteering column of a motor vehicle instead of the lever |4| it will beobvious that this can be arranged by causing the preselector lever tomove cams which impart the hereinbe'fore described motions to the linksI3 and |40.

If the interconnection with the clutch is eliminated, the abovedescribed mechanism becomes 5 a servo operating mechanism for the gearbox, which in some cases would be preferable to a preselectivemechanism.

Although in the drawings the first gear change mechanism has beendescribed as being provided 10 with plain dog clutches and nosynchronizing mechanism, it is to be understood that synchronizingmechanism may be provided on the first speed change mechanism as well asthe second. However such synchronizing clutches can be of smalldimensions and simplified type inasmuch as they have only to deal withthe inertia of the gears themselves.

Furthermore, although in the actual constructions described the drivenshaft is constituted by a shaft in line with the driving shaft it willbe understood that it is within the scope of the 1nvention to take thedrive from the layshaft (such as the shaft 232 in Figure 1). The driveis then indirect on all speeds but by properly proportioning the pinionssatisfactory ratios can be obtained and as this gives a lower positionfor the driving shaft it offers advantages in certain cases.

I claim:-

1. Power transmitting mechanism comprising rst and second ratio changingdevices arranged in series, each device having an input element and anoutput element, the first device adapted to receive power from theengine and the second adapted to deliver power to the drive wheels, theoutput element of the rst device and the input element of the seconddevice rotatable as a unit. clutches associated with said deviceswhereby the speed ratio of its output element to its input element maybe varied, together with synchronizmg means associated with the clutchof the second device only whereby, by shifting the first clutch todriving position before the second, synchronous shifting is availablefor all speeds together with means to operate the clutch of the firstdevice only when the clutch of the second device is vin its neutralposition.

2. Power transmitting mechanism comprising first and second ratiochanging devices arranged in series, each device having an input elementand an output element, the rst device adapted to receive power from theengine and the second adapted to deliver power to the drive wheels, theoutput element of the first device and the input element of the seconddevice rotatable as a unit, clutches associated with said deviceswhereby the speed ratio of its output element to its input element maybe varied, together with synchronizing means associated with the clutchof the second device only whereby, by shifting the first clutch todriving position before the second, synchronous shifting is availablefor all speeds together with means to operate the clutch of the firstdevice only when the clutch of the second device is in its neutralposition, said means including a lever movable in one direction tomanipulate one clutch and in a different direction to operate the otherclutch.

3. Power transmitting mechanism comprising rst and second ratio changingdevices arranged in series, each device having an input element and anoutput element, the rst device adapted to receive power from the engineand the second adapted to deliver power to the drive wheels, the

output element of the ilrst device and the input element ol' the seconddevice rotatable as a unit, clutches associated with said deviceswhereby the speedy ratio of its output elementto its input eiement maybe varied, together with synchronizing means associated with the clutchof the second device only whereby, by shifting the rst clutch to drivingposition before the second, synchronous shitting is available for allspeeds together with means to operate the clutch of the first deviceonly when `the clutch of the second device is in its neutral position,said means includingv a lever movable in one direction to manipulate oneclutch and in a different direction to operate the other clutch, and a.stop to prevent said lever from manipulating the rst clutch when thesecond clutch is engaged.

PIO FRANC() MARTINUZZI.

